MCP Server Template

/** * Configuration management with Zod validation * * Environment variables are prefixed with MCP_SERVER_ to avoid conflicts. * All configuration is validated at startup for fail-fast behavior. */ import { z } from 'zod'; import dotenv from 'dotenv'; // Load environment variables from .env file dotenv.config(); /** * Configuration schema with defaults and validation */ const ConfigSchema = z.object({ // Server identification serverName: z.string().default('mcp-server-template'), serverVersion: z.string().default('0.1.0'), // Logging logLevel: z .enum(['debug', 'info', 'notice', 'warning', 'error', 'critical']) .default('info'), logToFile: z.boolean().default(false), logDir: z.string().default('.logs'), // Database/Cache dbPath: z.string().default('.data/cache.db'), cacheEnabled: z.boolean().default(true), cacheTtlSeconds: z.number().positive().default(3600), // 1 hour default // Timeouts requestTimeoutMs: z.number().positive().default(30000), // Observability sentryDsn: z.string().optional(), otelEnabled: z.boolean().default(false), otelEndpoint: z.string().optional(), // Feature flags debugMode: z.boolean().default(false), }); export type Config = z.infer<typeof ConfigSchema>; /** * Parse environment variables into typed configuration */ function parseEnvConfig(): Config { const rawConfig = { serverName: process.env['MCP_SERVER_NAME'], serverVersion: process.env['MCP_SERVER_VERSION'], logLevel: process.env['MCP_SERVER_LOG_LEVEL'], logToFile: process.env['MCP_SERVER_LOG_TO_FILE'] === 'true', logDir: process.env['MCP_SERVER_LOG_DIR'], dbPath: process.env['MCP_SERVER_DB_PATH'], cacheEnabled: process.env['MCP_SERVER_CACHE_ENABLED'] !== 'false', cacheTtlSeconds: process.env['MCP_SERVER_CACHE_TTL'] ? parseInt(process.env['MCP_SERVER_CACHE_TTL'], 10) : undefined, requestTimeoutMs: process.env['MCP_SERVER_TIMEOUT'] ? parseInt(process.env['MCP_SERVER_TIMEOUT'], 10) : undefined, sentryDsn: process.env['MCP_SERVER_SENTRY_DSN'], otelEnabled: process.env['OTEL_ENABLED'] === 'true', otelEndpoint: process.env['OTEL_EXPORTER_OTLP_ENDPOINT'], debugMode: process.env['MCP_SERVER_DEBUG'] === 'true', }; // Remove undefined values so defaults apply const cleanConfig = Object.fromEntries( Object.entries(rawConfig).filter(([_, v]) => v !== undefined) ); return ConfigSchema.parse(cleanConfig); } // Cached configuration singleton let cachedConfig: Config | null = null; /** * Get validated configuration (cached after first call) */ export function getConfig(): Config { if (!cachedConfig) { cachedConfig = parseEnvConfig(); } return cachedConfig; } /** * Reset configuration cache (useful for testing) */ export function resetConfig(): void { cachedConfig = null; } /** * Validate configuration and return any errors */ export function validateConfig(): { valid: boolean; errors?: string[] } { try { parseEnvConfig(); return { valid: true }; } catch (error) { if (error instanceof z.ZodError) { return { valid: false, errors: error.errors.map((e) => `${e.path.join('.')}: ${e.message}`), }; } return { valid: false, errors: ['Unknown configuration error'] }; } }